This investigation addresses itself to the problem of fixation of total joint replacements using porous fiber metal composites. In addition, it also studies some aspects of the wear of the articulating surfaces in artificial joints. Some of the biocompatibility aspects of these two problems are also evaluated. The studies being conducted include: a) studies of the carcinogenicity of implant materials and porous materials, b) a canine total hip replacement, a total surface replacement and a total knee replacement model are evaluated to determine the efficacy of different types of configurations for fixation using porous materials, c) studies are in progress in the determination of magnitude of the problem of metal ion migration from porous composites from titanium and cobalt-chrome materials, d) an in vivo study on the wear magnitude of titanium surfaces articulating against UHMW polyethylene is in progress, e) the studies on the relationship between crystallinity of UHMW polyethylene and its mechanical properties on wear are also in progress.